Since I'm in CC, does this series aim to replace 2 patches I've tested before: blk-mq: add requests in the tail of hctx->dispatch blk-mq: align to legacy's implementation of blk_execute_rq ? On čtvrtek 31. srpna 2017 19:27:19 CEST Ming Lei wrote: > The current SCSI quiesce isn't safe and easy to trigger I/O deadlock. > > Once SCSI device is put into QUIESCE, no new request except for RQF_PREEMPT > can be dispatched to SCSI successfully, and scsi_device_quiesce() just > simply waits for completion of I/Os dispatched to SCSI stack. It isn't > enough at all. > > Because new request still can be allocated, but all the allocated > requests can't be dispatched successfully, so request pool can be > consumed up easily. > > Then request with RQF_PREEMPT can't be allocated, and system may > hang forever, such as during system suspend or SCSI domain alidation. > > Both IO hang inside system suspend[1] or SCSI domain validation > were reported before. > > This patch tries to solve the issue by freezing block queue during > SCSI quiescing, and allowing to allocate request of RQF_PREEMPT > when queue is frozen. > > Both SCSI and SCSI_MQ have this IO deadlock issue, this patch fixes > them all by unifying blk_freeze_queue() and blk_unfreeze_queue(). > > > [1] https://marc.info/?t=150340250100013&r=3&w=2 > > Ming Lei (9): > percpu-refcount: introduce percpu_ref_is_dead() > blk-mq: rename blk_mq_unfreeze_queue as blk_unfreeze_queue > blk-mq: rename blk_mq_freeze_queue as blk_freeze_queue > blk-mq: only run hw queues for blk-mq > block: introduce blk_drain_queue() > blk-mq: rename blk_mq_freeze_queue_wait as blk_freeze_queue_wait > block: tracking request allocation with q_usage_counter > block: allow to allocate req with REQF_PREEMPT when queue is frozen > SCSI: freeze block queue when SCSI device is put into quiesce > > block/bfq-iosched.c | 2 +- > block/blk-cgroup.c | 8 +++---- > block/blk-core.c | 49 > +++++++++++++++++++++++++++++++++-------- block/blk-mq.c | > 49 +++++++++++++++++++++-------------------- block/blk-mq.h > | 1 - > block/blk.h | 5 +++++ > block/elevator.c | 4 ++-- > drivers/block/loop.c | 16 +++++++------- > drivers/block/rbd.c | 2 +- > drivers/ide/ide-pm.c | 3 ++- > drivers/nvme/host/core.c | 8 +++---- > drivers/scsi/scsi_lib.c | 23 +++++++++++++++++-- > include/linux/blk-mq.h | 13 ++++++----- > include/linux/blkdev.h | 18 +++++++++++++-- > include/linux/percpu-refcount.h | 17 ++++++++++++++ > 15 files changed, 153 insertions(+), 65 deletions(-)
